Improvement in duplex telegraphs



C. H. HA$K|NS.

Duplex Telegraphs.

e I t m a W THE GRAPHIC CD, FNOTO-LITK 398 4-1 PARK PLACEVILY,

UNITED STATES PATENT OFFICE.

CHARLES H. HASKINS, OF MILWAUKEE, WISCONSIN.

IMPROVEMENT IN DUPLEX TELEGRA'PHS.

Specification forming part of Letters Patent No. 164,479, dated August 25, 1874; application filed April 14, 1874.

To all whom it may concern:

Be it known that 1, CHARLES H. HASKINS,

of Milwaukee, in the county of Milwaukee and State of Wisconsin, have invented certain Improvements in Electro-lvlagnetic Telegraphs, of which the following is a specification:

If a sin gle-line telegraph extending from one to another of two stations is provided at each station with a battery connected to the line by a key, and a current is sent into the line from both batteries simultaneously through a relay at each station, both. relays will indicate the passage of the current. Now, if the current from one of the batteries ceases, both relays will still continue to indicate the current from the other battery. If the relays are so constructed that the current from the battery at one station shall pass through both relays, but be indicated only at the relay of the other station, then it will be possible to. send a signal from both stations, each to the other, at the same instant, because, at no time during the space of a signal from either end is there a break in the circuit, and at no time will a relay at one station indicate the passage of other than the current sent into the line from the other station. Therein consists the art of the simultaneous double transmission of telegraph-signals.

It will be seen that to practice this art two things are necessary: First, matters must be so arranged that the outgoing signal shall pass unindicated through the senders relay, and be indicated only at the receivers relay; second, matters must be so arranged that the manipulation of the key at either station shall not break the circuit as to the other station. In other words, the opening of a key at one station shall not prevent the other station from sending its battery-current through the line. The first of these conditions has been attained in several different ways, one ofw-hich consists in the employment of an equating local circuit, operated by the senders key and passing around the senders relay in such directionas to neutralize the effect upon said relay of the senders battery, applied by the same key at the same instant, while an incoming signal, passing around the core and through the receivers key to ground, does not have to overcome this neutralization, except at the one of the magnets, actuates the armature,

and passes to ground through the receivers key. Still another plan (which is virtually the same as the last) consists in dividing the senders current or outgoing signal, and.

causing it to pass through two wires wound around a single core in opposite directions, thus neutralizing each other, while the incoming signal passes through only one of these wires and through the receivers key to the ground. I

In all these plans it will be perceived that the incoming signal is made to pass throughone part of a double helix and through the receivers key to the ground; and the fact that the current must pass through the key necessitatesto preserve the second condition above stated-that the key itself shall be so constructed thata ground contact is constant from the line through one part of the double helix to key and to ground, in whatever posi-' tion the key may be. To accomplish this. preservation of a continuous contact various plans of threeTpoi-nt keys have been used.

In the present invention Idispense with the 1 ground contact for the key except when an outgoing signal is passing, and an incoming.

signal never reaches the receivers key except when said key is closed anl the additional.

force is required to overcome the senders own neutralization of I the relay. At the moment when no outgoing signal is passing, the in-,

coming signal passes through the relay and to ground through the permanently-connected rheostat. I

I use a simple Morse key, without a groundwire attachment, combined with a relay so constructed or arranged that when the key is openthat is, not connected to the batterythe incoming current, passing to ground.

through both coils of the relay and thence through the rheostat, will so magnetize the relay core or cores as to close the armature:

and make a signal; while, when the key is cosed, its battery-current will divide to line and to rheostat, neutralizing the relay.

My invention consists of a relay for double transmission made in the following manner: Two separate cores are wound, and the helices connected together in such a manner that the same ends of the cores will be of the same polarity when the current enters the wire connecting the two and divides to each, but of opposite polarity when it enters either end of the helix-wire and passes from one to the other; all in connection with a polarized armature or armatures suspended between the ends of the cores, or prolongations thereof, so that the cores, when similarly polarized, will both attract the positive end of the armature and repel the negative end, keeping it stationary, and when oppositely polarized one core will attract the positive and repel the negative, while the other will attract the negative and repel the positive end of the same armature, closing it upon the contact-points. My invention consists, further, in combining with a relay, substantially such as is indicated above, and the open Morse key, a condenser for neutralizing the effect of the static discharge of the current from the line back through the relay, so arranged that the condenser shall discharge its current into the same wire surrounding the relay. The condenser-cinrent thus meets the static current upon the same wire, and opposing they neutralize each other. This, it will be seen, is different from sending a condenser-current by a separate wire around the helix in the opposite direction to that taken by the static-discharge current, as is commonly done. All of which will be more fully understood by reference to the drawings and following description.

In the accompanying drawings, which form a part of this specification, Figure 1 is a plan, and Fig. 2 a front elevation, of my improved relay. Figs. 3, 4, and 5 are diagrams illustrating the operation of the relay with simple Morse key, without ground-connection, in double transmission.

In the said drawing, A A are the two helices of my improved relay. They are wound or connected so that the current passes as indicated by the arrows, when the current is sent in from the line. The helix A, which is the rheostat side helix, is mounted in a frame, a, which slides in a bed-plate, b, and may be adjusted by the screw 0 toward or away from the other helix and the armature. These helices lie parallel to each other, and their cores are fitted with the semicircular core prolongations O O at both ends. Between the two helices lies the shaft D, carrying at each end a polarized armature, B, (a permanent magnet,) with its negative pole at the top and its positive pole below, at one end, and the reverse at the other end of the shaft. These duplicate armatures stand between the ends of the prolongations C G, which are within effective distance of said armatures. Centrally upon the shaft D is the vibrating contact-arm E, carrying the cores are polarized oppositely.

contactpoint 0, playing toward the contactpoint 0 upon the contact-arm E. F is the common tension-s1' ring to regulate minute variations and hold the points apart. The linewire is connected to the binding-post G, the wire from the key is connected to the bindingpost G and the wire to the rheostat is connected to post G The posts H H are for connecting the local sounder with the contactpoints 6 e.

In the diagrams, Figs. 3, 4, 5, K represents a common Morse key, having two points only, one of which is connected to the battery L, and one to the wire M, which connects to the wire m, which passes from one helix to the other of the relay. The line-wire is connected to the helix A, and the rheostat N is connected to the helix A. The manner of winding the helices will be clearly understood from the diagram.

The batteries at the terminal stations of the line are connected the same as in ordinary Morse lines-that is to say, if the positive pole of a battery at one terminal station is connected to line, the battery at the other terminal station must be connected negative pole to line.

The operation is as follows: Suppose, as a first state of aifairs, that the line is free; then, as indicated at Fig. 3, the key K may be closed, and a current from battery L sent into the wire M. This current will divide at its junction with the connecting-wire m, and pass one part to line around the helix A, and the other part to ground around the helix A, and through the rheostat. the same around ,both helices, producing like polarity in their cores at like ends. The core n-olongations (J G are polarized, as indicated in Fig. 3. One end of the armature is, therefore, attracted by both, and the other end rcpelled by both, said armature B being a magnet; it, therefore, remains stationary.

In a second state of afiairs, while this current from the battery L is still passing, as indicated, the key K being still closed, suppose at a distant station another current be sent into the line from another battery; the circuit occupied by this additional force will include the helix A and key K, but will not include the helix A, because it finds an easier path to ground by Way of battery L. The effect will be that the helix A will overcome the helix A, because it possesses the strongest current. Its magnet being therefore the strongest will, acting both by attraction and repulsion upon the two poles of the armature, cause it to swing and close the contact-points, making the signal of a duration just equal to the duration of the distantlyapplied additional force.

In a third state of afi'airs, suppose the key K to be open. Now, if a distant station sends a signal into the line it passes around the helix A in one direction and around the helix A in the other direction. The result is that the One end or The direction of the current is pole of the armature is repelled at one side and attracted at the other, and the other pole, vice versa, closing the contact-poin ts byswinging thearmature, and thus making the signal. Let it be remarked here in this connection that the armature is now acted on by two magnets, and therefore the force of one need be but half what it need be under thepreviou'sly' stated conditions.- This compensates for the increased resistance encountered in the rheostat, which is escaped in the other conditions by the easier passage of the incoming dispatch through the closed key.

These three states of affairs are the only ones which can occur in the working of the instrument; and it will be seen that the invention therefore fulfils both of the two conditions statedin the preamble as necessary to double transmission with an open Morse key.

It will,'of course, be understood that the mechanism shown in the diagram duplicated at all stations.

When the key It is opened, and consequently the tension of the battery removed, the current in the line appears to reverse momentarily at the instant, and flows back through the relay, producing a false signal. This static discharge, as it is termed, only occurs on long lines, but upon long lines it must be overcome.

To overcome this effect in this system of double transmission, where the open key is used, the condenser l is applied to the wire between the helix A and the-rheostat N. Now; when the key is closed the battery-current fills the condenser, and when the key is opened the static discharge takes place, and is met and neutralized in the same wire by theinstantaneous discharge of a current in the opposite direction from the condenser.

I arm-aware that a condenser has been herenected first to the line-wire.- The two cur rents passing through the helices around the core or cores in opposite directions neutralize their effect upon the core, while inmy invention the condenser-current heads against the static current in the same wire, and the result is they neutralize-each other. v

Having thus described myinvention, I claim as new and desire to secure by Letters Patent- 1. The relay, composed of two separate cores wound with helices in such manner that a current will pass in opposite directions around said cores when said current enters said helices from either of the free ends, one of said free ends being connected to line and the other to ground, in combination with the permanent-magnet armature and the Morse key connected to both helices, between said 1 helices, substantially as specified.

2. The combination of the helices A A, the parallel cores provided with semicircular prolongations G0, the polarized armatures B,"

shaft D, contact-points e e, and the wire M,

substantially as specified.

attached to the connection m, and the key K, r

3. The combination,with the relay, substantially as specified, of the condenser P and the Morse key K,'connccted, arranged, and oper;

ating essentially as specified.

Witnesses v A. WELLER, I). H. HENSHAW.

on; H. AsKms, 

